Adenocarcinoma of the appendix is a rare entity with a reported incidence of .03 to .08 per cent. A review of all appendectomies performed at St. Joseph Mercy Hospital (a private community hospital) between 1963 and 1979 was undertaken to assess the efficacy of preoperative diagnosis. Six adenocarcinomas were found, consisting of five male patients and one female patient with a mean age of 65 years. Symptoms were present for 24 hours or greater in all cases. A preoperative diagnosis was not made in any patient. Three patients later required a definitive therapeutic procedure, and two patients died from metastatic disease during their initial hospitalization. The literature was reviewed to evaluate methods of preoperative and intraoperative diagnosis of appendical adenocarcinoma. A suspicion of carcinoma of the appendix should be entertained for patients over the age of 50 years who present with signs and symptoms of appendicitis for greater than 24 hours. A barium enema performed preoperatively and especially a frozen section at the time of surgery of any suspicious appendiceal lesions may improve the diagnostic accuracy and survival of patients with this disease entity. If preoperative or intraoperative diagnosis is made, the patient can be better prepared and definitive surgical therapy carried out. This avoids delay in treatment and a second operative procedure.